Progressive Lower Extremity Weakness and Axonal Sensorimotor Polyneuropathy from a Mutation in KIF5A (c.611GA;p.Arg204Gln)

Introduction. Hereditary Spastic Paraplegia (HSP) is a rare hereditary disorder that primarily involves progressive spasticity of the legs (hamstrings, quadriceps, and calves).Methods. A 27-year-old gentleman was a fast runner and able to play soccer until age 9 when he developed slowly progressive weakness. He was wheelchair-bound by age 25. He was evaluated by laboratory testing, imaging, electrodiagnostics, and molecular genetics.Results. Electrodiagnostic testing revealed an axonal sensorimotor polyneuropathy. Genetic testing for HSP in 2003 was negative; repeat testing in 2013 revealed a mutation in KIF5A (c.611G>A;p.Arg204Gln).Conclusions. A recent advance in neurogenetics has allowed for more genes and mutations to be identified; over 76 different genetic loci for HSP and 59 gene products are currently known. Even though our patient had a sensorimotor polyneuropathy on electrodiagnostic testing and a 2003 HSP genetic panel that was negative, a repeat HSP genetic panel was performed in 2013 due to the advancement in neurogenetics. This revealed a mutation inKIF5A.